Intestinal barrier defects are involved in the pathogenesis of inflammatory bowel disease. The present study investigated the ameliorative effects of naringenin, a citrus polyphenol, on intestinal tight junction (TJ) barrier defects and inflammation in a murine model of colitis. In Expt. 1, using a 2 × 2 fractional design, the mice were administered water or 2% dextran sulfate sodium (DSS) in combination with feeding control or naringenin-containing diets for 9 d (severe disease stage). DSS administration caused severe colon damage and inflammation, as indicated by body weight loss, increased clinical sores, colon shortening, and gene expressions of inflammatory cytokines [interferon-γ, interleukin (IL)-6, macrophage inflammatory protein-2, and IL-17A). DSS administration also impaired TJ barrier integrity in the colon, as indicated by increased colon permeability and plasma LPS-binding protein levels, resulting from the impaired colonic expression of TJ proteins, occludin, junctional adhesion molecule-A, and claudin-3. Supplemental feeding with naringenin totally or partially attenuated these symptoms, suggesting that naringenin ameliorates the DSS-induced colitis at least partially through protection of the TJ barrier. In Expt. 2, analyses were performed at different disease stages (d 3, 6, and 9) to more widely examine the ameliorative role of naringenin on the initiation and development of colitis. DSS administration moderately induced colon shortening at d 3 and 6 and increased the disease activity index (DAI) and inflammatory cytokine (IL-6 and IL-17A) expression without any significant increases in colonic permeability. Feeding naringenin attenuated the increased DAI and colon shortening and tended to suppress the increased cytokine expression. These findings suggest that the presence of an additional mechanism underlying the naringenin-mediated, anticolitic effect along with barrier protection.

This study targets the evaluation of melanin synthesis inhibition activity of the bamboo shoot skin as agro-waste. The total methanolic extract of bamboo peel extract was evaluated for its skin protective effects via measuring its melanin inhibitory activity and its suppression activity on the expression of tyrosinase mRNA levels. Results showed that bamboo peel extract has a good ability for the inhibition of melanin synthesis so further studies were performed for the isolation of its constituents. Twelve compounds have been isolated from the shoot skin of Phyllostachys pubescens. Their structures were elucidated based on extensive spectroscopic methods. The melanin inhibition potential of the isolates was tested with their collagen-production-promoting activity for the determination of active principles. Results showed that Betulinic acid, tachioside, and 1,2-dilinolenin significantly suppressed melanin production per cell compared to control. Triacontanol, tricin, and (+)-lyoniresinol 9′-O-glucoside also tended to decrease melanin production per cell. These findings indicated that the skin of bamboo shoots, a significant agricultural waste, is a useful natural source for further research on its potential for aging problems such hyperpigmentation and cognitive function impairment.